need help on my system

i just connected a system on my truck its single cab chevy and i recently purchased infinity components with the q logic kick panel. and i recently made a new sealed box for my 3 10 inche subs with a 1000 watts amp . ok after connection when i turned it on the bass like comes and goes on different songs i play. cause it plays some songs ok and some it doesn't. then it throws no bass also now the highs are fading up and down while the lows also go up and back down . to me its sounds like if the lows go up and highs go down. dont know what the problem could be